Oven thermometer



March 17, 1925. 1,530,258

c. l. HALL OVEN THERMOMETER Filzd No v. 12 1920 His Acborrey.

tween the prima device and are .therefore sub ec t 110 Patented Mar. 17, 1925.

CHES'IER I. HALL, OF

FORT WAYNE, INDIANA, ASSIGNOR T0 GENERAL ELE'C'IRIC COM- IANY. A COBPO-B-A'IION OF NEW'YORK.

ov1m mmzmuommn'm.

Application T0 all wlaom z't may concern:.

Be it known that I, CHESI'ER I. HALL, a,

citizen cf the United Stabes,

Fort W ayne, in

the county of Allen,

residing at State of Indiana, have invented certain new an useful Ixnprovements m Oven Thermometers, of which the following is a tion.

te1's and has for its object the pr Specificainvention relates to oven thermomef Ing. 2 1s a sect1on v1ew along the 'hne 2--2 -0f Fig. 1.

ovision 0 means whereby the temperature of an oven may be indicated in a sunple, etfic1ent manner.

More spec1fically my mvenhon reliable and reiates 130 thermometers for indicating the temperature ofbvens although it has othe1 apphcut1ons.

A great deal of trouble has enced with oven fact that they have' heretofore vided with gearing 01' leverage mover and the tiona1 effects and inaccuracies, su

motion. due to improper machining an r hng of the parts.

An excessive also been expenenced been experithermometers due to the been pro- 1atios beindicating fr;ic 011 as lost d fittime lag has due 130 the practice of so attaching oven thermometers that they a1e practically an integral art of the oven door and are aifected by the temperature 0f the oven by conduction through door. This causes the a time lag often the oven thermometer to have of considerable duration before the temp erature of the air at the centcr of the oven 1s indicated.

In carrying out my 1nvent1on Iusea thennostatic metal element which is attached directly to the indicator thus e1nninating all gear anc1 1eyer connect ions, and I mount the thermostat1c element m a perforated casing which projects into through the 1nner the oven lining of the same thus exposing the thermostatic element directly ro the temperature of the air in By constructing my manner the oven.

thermometer in this I obtain a dev1ce Wh10h 1s accurate and reliable and which will respond to the temperature 0f the air in time lag of less than two minutes. I also provide a zero adjust-men easily accessible either before 01 device is mounted in the oven.

the oven with a t which iS after the The co nstruction of my device permits the use of a very long equ1crescent sca le thereby fllet1 November'l2, 1920. Serial N0. 423,701.

obtaining greater legibility as weil as indi- .cations ot' smaller 'temperature variations.

Referring to the drawings, a thermostatic metal element 12 in the form of a spiral is mounted in a casing consisting of a cylindrical portion 10 attached at the Iower ond to a perforatedbase 11 an l provi led at the upper end with a sca1e 15 calibrated in degrees. Oneend 0f the thermostatic element 1s 100pd loosely around a supporting pin 16 which is const-rained to be moved in an arc about bearing 18 by means of a strip 17 attached thereto and pivoted at the point 18. T he pin 16 is held in position by means of a screw 22 Which may be moved in an open1ng or slot 23 in the base foi the pm pose of adjusting the position of the pin. The other end 0f the therrnostatic ele1ne1it is rigidly attached 130 a pointer stafl 13 Which is rotatably supported on the base at central bearing 18 and projects through the center of the calibrated scale 15. Tlie upper end of the pointer stafl' 13 carries a pointer 14 arranged to move over the Calibrated scale. A glass protecting face 19 is attached to the cylindrical portion 10 by means of metal rings 20 and 21 in a Weil known manner. The casing is provided with projecting ears 24 situated a short distance above the base, f0 1 the purpose of attaching the device to the oven.

As thus constructed the 'thermometer is adapted t0 be attached to the oven dem with the eylindrical portion 10 of the casing ex tending through the Wall of the oven and With the perforated base portion 11 projecting a short distance Within the oven. The calibrated scale is thus exposed so as t0 be read from without the oven and the thermostatie element is in direct con ach with the air in the oven by means of the perforations.

It will be seen that by using a thermostatic element in the shape .of a spiral I am enabled t0 connect the thermostatic element directly t0 the indicating device. Upon changes of temperature the thermostatic element will be afl'ected in such a manner that the pointer stafl Will be turned in one direction 01 the other, thus moving the pointer over the sca le und giving an indication of the temperature in the oven.

A the1mostatic element of this character will give a wide range 0f movementof the indicating device, and I am thereby enabled to use a calibrated scale haVing relatively large increments. The scale is thus made more legible and smaller changes of temperature can be indicated upon it.

The pin 16 is so arranged that it may be loosened by means of screw 22 and moved to adjust the ze1o calibration of the instrument at any time either before or after the instrument is mounted in the oven.

In accordance With the provisions cf the patent statutes, I have described the principle of operation of my invention, 1:0- gether with the apparatus whivh I 110W cousider to. represent the best embodiment thefeof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carrred 0ut by other means.

What I claim as new and desire to secure I y Letters Patent of the United Staates, 1s:-

1. An oven thermometen comprising a casing, indicating means carried by said casing, a thermostatic element operatively connected to said indicating means, an arm pivoted in said casin,q forming an adjustable support f0r said thermostatic element,

there being an arcuate slot in said casing,

and clamping means f0r said arm extending through said slot and accessible fro1n The exterior 0f said casing.

2. An oven thermometer comprising a casing, a pointer stafl rotatably mounted in said casing, a pointer carried by said staff, a spiral thermostatic elementhaving one end secured t0 said stnfi';an arm having 0ne end secured t0 the other end of said thermostatic element and pivoted about the axis 0f rotation of said stafl:' whereby said thermostatic element may be adjusted to effect the zero setting 0f said pointer, there being an arcuate slot in said casing, and a clamping screw for said arm extending through said slot and accessible from the exterior of said casing.

In witness Whereof, I have hereunto set my band this 8 day of Nov., 1920.

' CHESTER I. HALL. 

